[Effects of winter cover crop on methane and nitrous oxide emission from paddy field]

Static chamber-GC technique was employed to study the effects of different treatment winter cover crops, including no-tillage and directly sowing ryegrass (T1), no-tillage and directly sowing Chinese milk vetch (T2), tillage and transplanting rape (T3), no-tillage and directly sowing rape (T4), and fallowing (CK), on the CH4 and N2O emission from double cropping rice paddy field. During the growth period of test winter cover crops, the CH4 and N2O emission in treatments T1-T4 was significantly higher than that in CK (P < 0.01). Treatments T1 and T3 not only had the largest CH4 emission (0.60 and 0.88 g x m(-2)), but also had the largest N2O emission (0.20 and 0.23 g x m(-2), respectively). After the winter cover crops returned to field, the CH4 emission from early and late rice fields in treatments T1, T2, T3, and T4 was larger than that in CK. In early rice field, treatments T1 and T2 had the largest CH4 emission (21.70 and 20.75 g x m(-2)); while in late rice field, treatments T3 and T4 had the largest one (58.90 and 54.51 g x m(-2) respectively). Treatments T1-T4 also had larger N2O emission from early and late rice fields than the CK did. The N2O emission from early rice field in treatments T1, T2, T3, and T4 was increased by 53.7%, 12.2%, 46.3%, and 29.3%, and that from late rice field in corresponding treatments was increased by 28.6%, 3.8%, 34.3%, and 27.6%, respectively, compared with CK.

Characterization, quantification, and yearly variation of the naturally occurring polyphenols in a common red variety of curly kale ( Brassica oleracea L. convar. acephala var. sabellica cv. 'Redbor')

This study focuses on the characterization and quantification of polyphenols in the edible leaves of red curly kale ( Brassica oleracea L. convar. acephala (DC.) Alef. var. sabellica L.), variety 'Redbor F1 hybrid'. The kale was grown at an experimental field (59° 40' N) in the years 2007-2009. The analysis of kale extract by HPLC-DAD-ESI-MS has allowed the determination of 47 different acylated and nonacylated flavonoid glycosides and complex hydroxycinnamic acids. Those compounds included mono- to tetraglycosides of quercetin, kaempferol, and cyanidin and derivatives of p-coumaric, ferulic, sinapic, and caffeic acid. Among the compounds characterized, four flavonols, three anthocyanins, and three phenolic acids were identified in the Brassica family for the first time. Aglycones and conjugated polyphenols were quantified by HPLC-DAD using commercially available standards. The main flavonol, anthocyanin, and phenolic acid were kaempferol-3-sinapoyl-diglucoside-7-diglucoside, cyanidin-3-sinapoyl-feruloyl-diglucoside-5-glucoside, and disinapoyl-diglucoside, respectively, each representing 9.8, 10.3, and 4.9% of the total amount of 872 mg polyphenol equivalents per 100 g of fresh kale. Variations between individual plants and growing seasons were of the same order of magnitude for total phenolics and total monomeric anthocyanins.

Elucidating the process of co-composting of biosolids and spent activated clay

This study elucidates the co-composting of biosolids and spent activated clay (SAC) using physio-chemical, bioassay, and spectroscopic methods. A pilot-scale pile of blended limed biosolids, SAC, and rice husk was composted for 15weeks. The changes in temperature, pH, Fourier-transform infrared (FT-IR) spectra, C/N, and germination index (GI) of Chinese cabbage (Brassica chinensis) seeds with time support the goal of producing a mature compost with a decline in the SAC acidity of associated with biosolids. Cadmium, Cr, Cu, Ni, and Pb in the initial biosolids were converted from labile fractions into relatively immobile phases upon maturation. Temperature, moisture, pH, C/N, and GI were used to separate the composting process into three phases - initial, thermophilic, and cooling, based on a score plot of principal component analysis (PCA). The values of the parameters of interest reveal that the compost fulfills the requirements of compost maturity in the literature.

Seed coat phenolics and the developing silique transcriptome of Brassica carinata

Structures for nine compounds were elucidated in seed coats of two genetically related Brassica carinata lines. The yellow-seeded line accumulated monomeric kaempferols, phenylpropanoids, and lignans, while extractable and unextractable proanthocyanidins and a high-performance liquid chromatography peak containing polymeric-like quercetin/lignan structures were strongly reduced. The brown-seeded line accumulated large amounts of both types of proanthocyanidins (extractable and unextractable), as well as phenylpropanoids and lignans equivalent to the amounts in the yellow-seeded seed coats, but the brown-seeded seed coats lacked kaempferols. A Brassica napus 15K oligoarray experiment indicated that yellow-seeded siliques had more extreme gene expression changes and a 2.4-fold higher number of upregulated genes than brown-seeded siliques, including a host of transcription factors and genes with unknown function. Transcripts for six flavonoid genes (CHS, F3H, FOMT, DFR, GST, and TTG1) were lower and two (F3'H and FLS) were higher in yellow-seeded siliques, but expression of CHI, PAP1, and phenylpropanoid genes was unchanged.

Inoculation of food waste with the thermo-tolerant lipolytic actinomycete Thermoactinomyces vulgaris A31 and maturity evaluation of the compost

The ability of the thermo-tolerant lipolytic actinomycete, Thermoactinomyces vulgaris A31, to efficiently decompose food waste into mature compost was studied. Using a range of chemical parameters (pH, total organic carbon content (TOC), total nitrogen content, C/N ratio), CO(2) evolution, enzymatic activities (dehydrogenase, polyphenol oxidase, urease) and germination assays, the composition, stability and maturity of the compost produced were assessed. Inoculation reduced crude fat and decreased the maturation time of the compost when compared with the control. TOC, C/N ratio, CO(2) evolution, and enzymatic activities (dehydrogenase, polyphenol oxidase, urease) decreased, pH, total nitrogen content, germination rate, and germination index increased. The dehydrogenase, polyphenol oxidase, and urease activities were shown to be useful indicators for the stability of food waste composts. Based on germination assays, the food waste composts were phytotoxicity free and matured after composting for 2 months. Therefore, inoculation of food waste with the thermo-tolerant lipolytic actinomycete, T. vulgaris A31, presents as a feasible strategy to convert food wastes into mature compost efficiently.

Interaction of 8-hydroxyquinoline with soil environment mediates its ecological function

Background

Allelopathic functions of plant-released chemicals are often studied through growth bioassays assuming that these chemicals will directly impact plant growth. This overlooks the role of soil factors in mediating allelopathic activities of chemicals, particularly non-volatiles. Here we examined the allelopathic potential of 8-hydroxyquinoline (HQ), a chemical reported to be exuded from the roots of Centaurea diffusa.

Methodology/Principal Findings

Growth bioassays and HQ recovery experiments were performed in HQ-treated soils (non-sterile, sterile, organic matter-enriched and glucose-amended) and untreated control soil. Root growth of either Brassica campestris or Phalaris minor was not affected in HQ-treated non-sterile soil. Soil modifications (organic matter and glucose amendments) could not enhance the recovery of HQ in soil, which further supports the observation that HQ is not likely to be an allelopathic compound. Hydroxyquinoline-treated soil had lower values for the CO₂ release compared to untreated non-sterile soil. Soil sterilization significantly influenced the organic matter content, PO₄-P and total organic nitrogen levels.

Conclusion/Significance

Here, we concluded that evaluation of the effect of a chemical on plant growth is not enough in evaluating the ecological role of a chemical in plant-plant interactions. Interaction of the chemical with soil factors largely determines the impact of HQ on plant growth.

Characterization of nucleases involved in seedling development of cauliflower

The ability of cells to control the degradation of their own DNA is a common feature of most living organisms. In plants, extensive hydrolysis of nuclear DNA occurs during different forms of programmed cell death (PCD). In addition to the removal of unwanted cells, the PCD process allows for the remobilization of cellular constituents, including the products of DNA hydrolysis. Although programmed cell death occurs widely during normal development and plant defense responses to pathogens, only one class of deoxyribonucleases, the S1 type, involved in these processes, has been well characterized. Using DNA-SDS-PAGE, we identified the activities of 14 deoxyribonucleases expressed in different organs of cauliflower seeds, seedlings and the flower head. These enzymes represent several classes based on their substrate specificity and ion dependency. In addition to four Zn(2+)-dependent enzymes, we identified five Ca(2+)-dependent, two Mg(2+)-dependent, three Ca(2+)/Mg(2+)-dependent and one nuclease whose activities seem to be independent of any divalent cations. We also identified a set of DNases whose expression seems to be common for different organs and different stages of development, as well as a few highly tissue-specific nucleases. Expression of three nucleases was inducible by drought stress and hydrogen peroxide.

[Effects of simulated acid rain on oilseed rape (Brassica napus) physiological characteristics at flowering stage and yield]

A pot experiment was conducted to study the effects of different acidity simulated acid rain on the physiological characteristics at flowering stage and yield of oilseed rape (B. napus cv. Qinyou 9). Comparing with the control (pH 6.0), weak acidity (pH = 4.0-5.0) simulated acid rain stimulated the rape growth to some extent, but had less effects on the plant biomass, leaf chlorophyll content, photosynthetic characteristics, and yield. With the further increase of acid rain acidity, the plant biomass, leaf chlorophyll content, photosynthetic rate, antioxidative enzyme activities, and non-enzyme antioxidant contents all decreased gradually, while the leaf malonyldialdehyde (MDA) content and relative conductivity increased significantly. As the results, the pod number per plant, seed number per pod, seed weight, and actual yield decreased. However, different yield components showed different sensitivity to simulated acid rain. With the increasing acidity of simulated acid rain, the pod number per plant and the seed number per pod decreased significantly, while the seed weight was less affected.

Brassicaceae INDEHISCENT genes specify valve margin cell fate and repress replum formation

Members of the Brassicaceae family, including Arabidopsis thaliana and oilseed rape (Brassica napus), produce dry fruits that open upon maturity along a specialised tissue called the valve margin. Proper development of the valve margin in Arabidopsis is dependent on the INDEHISCENT (IND) gene, the role of which in genetic and hormonal regulation has been thoroughly characterised. Here we perform phylogenetic comparison of IND genes in Arabidopsis and Brassica to identify conserved regulatory sequences that are responsible for specific expression at the valve margin. In addition we have taken a comparative development approach to demonstrate that the BraA.IND.a and BolC.IND.a genes from B. rapa and B. oleracea share identical function with Arabidopsis IND since ethyl methanesulphonate (EMS) mutant alleles and silenced transgenic lines have valve margin defects. Furthermore we show that the degree of these defects can be fine-tuned for crop improvement. Wild-type Arabidopsis produces an outer replum composed of about six cell files at the medial region of the fruits, whereas Brassica fruits lack this tissue. A strong loss-of-function braA.ind.a mutant gained outer replum tissue in addition to its defect in valve margin development. An enlargement of replum size was also observed in the Arabidopsis ind mutant suggesting a general role of Brassicaceae IND genes in preventing valve margin cells from adopting replum identity.

Quantifying the thermal heat requirement of Brassica in assessing biophysical parameters under semi-arid microenvironments

Evaluation of the thermal heat requirement of Brassica spp. across agro-ecological regions is required in order to understand the further effects of climate change. Spatio-temporal changes in hydrothermal regimes are likely to affect the physiological growth pattern of the crop, which in turn will affect economic yields and crop quality. Such information is helpful in developing crop simulation models to describe the differential thermal regimes that prevail at different phenophases of the crop. Thus, the current lack of quantitative information on the thermal heat requirement of Brassica crops under debranched microenvironments prompted the present study, which set out to examine the response of biophysical parameters [leaf area index (LAI), dry biomass production, seed yield and oil content] to modified microenvironments. Following 2 years of field experiments on Typic Ustocrepts soils under semi-arid climatic conditions, it was concluded that the Brassica crop is significantly responsive to microenvironment modification. A highly significant and curvilinear relationship was observed between LAI and dry biomass production with accumulated heat units, with thermal accumulation explaining >or=80% of the variation in LAI and dry biomass production. It was further observed that the economic seed yield and oil content, which are a function of the prevailing weather conditions, were significantly responsive to the heat units accumulated from sowing to 50% physiological maturity. Linear regression analysis showed that growing degree days (GDD) could indicate 60-70% variation in seed yield and oil content, probably because of the significant response to differential thermal microenvironments. The present study illustrates the statistically strong and significant response of biophysical parameters of Brassica spp. to microenvironment modification in semi-arid regions of northern India.

Role of Ca2+ on growth of Brassica campestris L. and B. juncea (L.) Czern & Coss under Na+ stress

Root and shoot growth of Brassica campestris L. and B. juncea increased significantly (P < 0.01) with enhanced Ca(2+) treatment along with 60 mM NaCl in the root medium. The maximum fresh mass of shoot and root in B. juncea was recorded at 10 mM Ca(2+) concentration. The relative growth rate of shoot of both species reached its maximum at 8 mM of Ca(2+) concentration. Average rate of Ca(2+) intake (I(Ca)) was higher in B. juncea than B. campestris. In B. juncea, the average transport of Ca(2+) to shoot increased by 19%, 38%, 119%, 125% and 169% compared with the control. Furthermore specific utilization rate of Ca(2+) was higher in B. juncea than B. campestris. In B. campestris it increased by 9%, 32%, 41% and 59% at 4, 6, 8, and 10 mM of calcium in comparison to 2 mM Ca(2+) treatment. At 4, 6, 8 and 10 mM of Ca(2+) application, the increase in the leaf area ratio was 10, 17, 23 and 30%, respectively. In the shoot and root portions of B. campestris and B. juncea, Ca(2+) had a linear relationship with potassium and sulfur, whereas it was in antagonism with sodium ion.

BoPMEI1, a pollen-specific pectin methylesterase inhibitor, has an essential role in pollen tube growth

Pectin methylesterase (PME) is known to have important roles in pollen development and pollen tube growth. As pivotal regulatory factors in PME activity modulation, PME inhibitors (PMEIs) are thought to be key regulators of cell wall stability at the tip of the pollen tube. We report on the cloning and characterization of a novel B. oleracea PMEI gene, BoPMEI1. Heterologously expressed BoPMEI1 showed PMEI activity. RT-PCR studies of different tissues and promoter-GUS fusions confirmed that BoPMEI1 was specifically expressed in mature pollen grains and pollen tubes. Based on in vivo transient assays, we found that BoPMEI1 appears to be largely localized to the plasma membrane. Transgenic Arabidopsis plants expressing antisense BoPMEI1 under the control of the CaMV 35S promoter suppressed the expression of the orthologous gene At1g10770, which led to partial male sterility and decreased seed set by inhibition of pollen tube growth. Our study demonstrates the involvement of BoPMEI1 in pollen tube growth.

Copper exposure interferes with the regulation of the uptake, distribution and metabolism of sulfate in Chinese cabbage

Exposure of Chinese cabbage (Brassica pekinensis) to enhanced Cu(2+) concentrations (1-10 microM) resulted in leaf chlorosis, a loss of photosynthetic capacity and lower biomass production at > or = 5 microM. The decrease in pigment content was likely not the consequence of degradation, but due to hindered chloroplast development upon Cu exposure. The Cu content of the root increased with the Cu(2+) concentration (up to 40-fold), though only a minor proportion (4%) was transferred to the shoot. The nitrate uptake by the root was substantially reduced at > or = 5 microM Cu(2+). The nitrogen content of the root was affected little at lower Cu(2+) levels, whereas that in the shoot was decreased at > or = 5 microM Cu(2+). Cu affected the uptake, distribution and metabolism of sulfate in Chinese cabbage. The total sulfur content of the shoot was increased at > or = 2 microM Cu(2+), which could be attributed mainly to an increase in sulfate content. Moreover, there was a strong increase in water-soluble non-protein thiol content in the root and, to a lesser extent, in the shoot at > or = 1 microM, which could only partially be ascribed to a Cu-induced enhancement of the phytochelatin content. The nitrate uptake by the root was substantially reduced at > or = 5 microM Cu(2+), coinciding with a decrease in biomass production. However, the activity of the sulfate transporters in the root was slightly enhanced at 2 and 5 microM Cu(2+), accompanied by enhanced expression of the Group 1 high affinity transporter Sultr1;2, and the Group 4 transporters Sultr4;1 and Sultr4;2. In the shoot, there was an induction of expression of Sultr4;2 at 5 and 10 microM Cu(2+). The expression of APS reductase was affected little in the root and shoot up to 10 microM Cu(2+). The upregulation of the sulfate transporters may be due not only to greater sulfur demand at higher Cu levels, but also the consequence of interference by Cu with the signal transduction pathway regulating the expression and activity of the sulfate transporters.

Glycerol as substrate for the production of biosurfactant by Pseudomonas aeruginosa UCP0992

In this work the influence of the carbon source concentration, of the type and concentration of the nitrogen source and of the cultivation conditions (temperature, aeration and agitation speed) in mineral medium formulated with glycerol was studied for biosurfactant production by Pseudomonas aeruginosa UCP0992. The kinetics of microorganism growth and biosurfactant production have been described for the medium supplemented with 3% glycerol and 0.6% NaNO(3), at 28 degrees C during 120 h under 200 rpm, showing a growth-associated production. The isolated biosurfactant corresponded to a concentration of 8.0 g/l after 96 h. The medium surface tension was reduced to 27.4 mN/m and the emulsification index of hexadecane reached 75-80% after 72 h. A CMC of 700 mg/l and an interfacial tension against hexadecane of 2 mN/m were obtained. The biosurfactant showed stability when submitted at 90 degrees C during 2 h, and thermal (4-120 degrees C) and pH (4-12) stability regarding the surface tension reduction and the emulsification capacity of vegetable oils and hydrocarbons, and tolerance under high salt concentrations (2-10%). The biosurfactant was characterized as a group of rhamnolipids with anionic nature. The crude biosurfactant did not show toxicity against the microcrustacean Artemia salina and the cabbage (Brassica oleracea), while the isolated biosurfactant showed toxicity against the microcrustacean at the CMC. The application of the biosurfactant in diesel recovery from sand was demonstrated by removal percentiles above 85%. The results obtained in this work are noteworthy for possible biosurfactant production from glycerol with potential of application in the environment.

[Effect of the melamine residue in soil on growth of Chinese cabbage]

Soil and foliar application of melamine (ME) treatments to 'Zaoshu 5' Chinese cabbage were investigated. The ME was degraded very slowly in soil treated with different dosages (40,160 and 800 mg x kg(-1)), and 90 days later the residuals of ME were 21.1%, 15.8% and 43.6% respectively. The Chinese cabbage could take in exogenously applied ME through its root and stem leaf and accumulate it to considerable levels with the increasing applied density. In soil application test, the maximum and minimum contents of ME were 105.7 and 8.0 mg x kg(-1) in root, and 139.9 and 7.1 mg x kg(-1) in stem leaf; the ME transport occurred from root to stem leaf. In foliar application test,the maximum and minimum contents of ME were 4.3 and 0.9 mg x kg(-1) in root, and 8.5 and 3.2 mg x kg(-1) in stem leaf. In soil application test,the low level of ME (40 mg x kg(-1)) increased the biomass yield by 9.8% and the high level of ME (800 mg x kg(-1)) decreased the biomass yield by 15.9%; the contents of chlorophyll and soluble sugar increased,but the content of Vitamin C decreased. Foliar application ME had no obvious significance on the growth of Chinese cabbage. The studies indicate that the residual time of ME in soil is long and the Chinese cabbage can absorb exogenously applied ME and ME can affect the growth of Chinese cabbage.

Influence of organic and conventional growing conditions on the nutrient contents of white head cabbage (Brassica oleracea var. capitata) during two successive seasons

Organically and conventionally grown white head cabbage (Brassica oleracea var. capitata) plants were cultivated during two successive seasons (spring and autumn) to evaluate the effects of the applications on the nutrient content of the edible part of cabbage plants. Seventeen different organic applications containing farmyard manure (FM), chicken manure (CM), and blood meal (BM) and 1 chemical fertilizer and 1 control, collectively 19 treatments, were examined under the open-field conditions. Recommendations of the best results obtained should be divided into groups in the following order regarding the mineral contents and also the seasons: 0.6 BM + 7.5 FM in the spring season, and 3.5 CM in the autumn season for N, P, and K content of cabbage. For Ca and Mg, the group division should be 1.7 CM + 0.6 BM in the spring season and 10.0 FM + 1.2 CM in the autumn season. The optimum recommendations for the micronutrients could be 5.0 FM + 1.0 BM in the spring season and 0.9 BM + 0.85 CM in the autumn season for Fe and Cu and 15.0 FM in the spring season, and 10.0 FM + 0.4 BM in the autumn season for Mn and Zn. FM and CM could be used in high rates in producing organic cabbage and could be substituted for chemical fertilizer especially in the spring season.

Intra-specific differences in root and shoot glucosinolate profiles among white cabbage (Brassica oleracea var. capitata) cultivars

Shoot glucosinolate profiles of Brassicaceae are known to vary within species, across environmental conditions, and between developmental stages. Here we study whether root profiles follow the intra-specific, environmental, and developmental variation observed for aerial parts in white cabbage cultivars. We also assess whether greenhouse studies can be used to predict shoot and root glucosinolate concentrations and profiles in the field. Root glucosinolate profiles showed significant intra-specific variation; however, this variation was unrelated to that in shoot profiles. One of the strongest determinants of the diversity in the root profiles was 2-phenylethyl glucosinolate (gluconasturtiin). Root profiles were generally comparable between greenhouse studies and field trials, whereas shoot profiles were highly plastic. We conclude that among white cabbage cultivars, shoot glucosinolate profiles are not indicative of root profiles. We further conclude that greenhouse assessments of root glucosinolates can be reliable predictors of root glucosinolate profiles in the field due to their low plasticity.

[The influence of colonizing methylobacteria on morphogenesis and resistance of sugar beet and white cabbage plants to Erwinia carotovora]

The influence of colonization of sugar beet (Beta vulgaris var. saccharifera (Alef) Krass) and white cabbage (Brassica oleracea var. capitata L.) plants by methylotrophic bacteria Methylovorus mays on the growth, rooting, and plant resistance to phytopathogen bacteria Erwinia carotovora was investigated. The colonization by methylobacteria led to their steady association with the plants which had increased growth speed, root formation and photosynthetic activity. The colonized plants had increased resistance to Erwinia carotovora phytopathogen and were better adapted to greenhouse conditions. The obtained results showed the perspectives for the practical implementation of methylobacteria in the ecologically clean microbiology substances used as the plant growth stimulators and for the plant protection from pathogens.

Mobilization and acquisition of sparingly soluble P-Sources by Brassica cultivars under P-starved environment II. Rhizospheric pH changes, redesigned root architecture and pi-uptake kinetics

Non-mycorrhizal Brassica does not produce specialized root structures such as cluster or dauciform roots but is an effective user of P compared with other crops. In addition to P-uptake, utilization and remobilization activity, acquisition of orthophosphate (Pi) from extracellular sparingly P-sources or unavailable bound P-forms can be enhanced by biochemical rescue mechanisms such copious H(+)-efflux and/or carboxylates exudation into rhizosphere by roots via plasmalemma H(+) ATPase and anion channels triggered by P-starvation. To visualize the dissolution of sparingly soluble Ca-phosphate (Ca-P), newly formed Ca-P was suspended in agar containing other essential nutrients. With NH(4)(+) applied as the N source, the precipitate dissolved in the root vicinity can be ascribed to rhizosphere acidification, whereas no dissolution occurred with nitrate nutrition. To observe in situ rhizospheric pH changes, images were recorded after embedding the roots in agar containing bromocresol purple as a pH indicator. P-tolerant cultivar showed a greater decrease in pH than the sensitive cultivar in the culture media (the appearance of typical patterns of various colors of pH indicator in the root vicinity), and at stress P-level this acidification was more prominent. In experiment 2, low P-tolerant class-I cultivars (Oscar and Con-II) showed a greater decrease in solution media pH than low P-sensitive class-II (Gold Rush and RL-18) cultivars, and P-contents of the cultivars was inversely related to decrease in culture media pH. To elucidate P-stress-induced remodeling and redesigning in a root architectural system, cultivars were grown in rhizoboxes in experiment 3. The elongation rates of primary roots increased as P-supply increased, but the elongation rates of the branched zones of primary roots decreased. The length of the lateral roots and topological index values increased when cultivars were exposed to a P-stress environment. To elucidate Pi-uptake kinetics, parameters related to P influx: maximal transport rate (V(max)), the Michaelis-Menten constant (K(m)), and the external concentration when net uptake is zero (C(min)) were tested in experiment 4. Lower K(m) and C(min) values were better indicative of the P-uptake ability of the class-I cultivars, evidencing their adaptability to P-starved environmental cues. In experiment 5, class-I cultivars exuded two- to threefold more carboxylates than class-II cultivars under the P-stress environment. The amount and types of carboxylates exuded from the roots of P-starved plants differed from those of plants grown under P-sufficient conditions. Nevertheless, the exudation rate of both class-I and class-II cultivars decreased with time, and the highest exudation rate was found after the first 4 h of carboxylates collection. Higher P uptake by class-I cultivars was significantly related to the drop in root medium pH, which can be ascribed to H(+)-efflux from the roots supplied with sparingly soluble rock-P and Ca(3)(PO(4))(2). These classical rescue strategies provided the basis of P-solubilization and acquisition from sparingly soluble P-sources by Brassica cultivars to thrive in a typically stressful environment.

Transcriptional regulation of anthocyanin biosynthesis in red cabbage

The color of red cabbage (Brassica oleracea var. capitata) is due to anthocyanin accumulation. To investigate the regulatory control of anthocyanin production in red cabbage, the expression of anthocyanin biosynthetic and regulatory genes from eight commercial cultivars was examined. While the four green varieties had negligible amount of anthocyanins under normal growth condition, the four red cultivars contained up to 1.60 mg g(-1) fresh weight. HPLC analysis of the four red cultivars revealed that they produced similar composition of various forms of cyanidin glucosides but at different concentrations. Molecular analysis indicated that all the red cabbage shared common mechanism of regulatory control for anthocyanin biosynthesis. Except CHI which showed similar expression levels between green and red cultivars, the other structural genes, CHS, F3H, F3'H, DFR, LDOX, and GST, were constitutively up-regulated during all stages of vegetative growth in red varieties. The expression of these structural genes was also dramatically increased in green and red cabbage under nutrient stresses. The increased expression of the structural genes coincided with a coordinated increase in transcript levels of a bHLH gene, BoTT8, and a MYB transcription factor, BoMYB2. These results indicate that activation of these two regulatory factors by unknown mechanisms constitutively up-regulates nearly the entire pathway genes for the onset of anthocyanin biosynthesis in red cabbage. Moreover, the amount of total anthocyanins in red cabbage was found to be positively correlated with total antioxidant power, implicating the potential health benefit of red cabbage to human health.

Mobilization and acquisition of sparingly soluble P-sources by Brassica cultivars under P-starved environment I. Differential growth response, P-efficiency characteristics and P-remobilization

Phosphorus (P) starvation is highly notorious for limiting plant growth around the globe. To combat P-starvation, plants constantly sense the changes in their environment, and elicit an elegant myriad of plastic responses and rescue strategies to enhance P-solublization and acquisition from bound soil P-forms. Relative growth responses, P-solublization and P-acquisition ability of 14 diverse Brassica cultivars grown with sparingly soluble P-sources (Rock-P (RP) and Ca(3)(PO(4))(2) (TCP)) were evaluated in a solution culture experiment. Cultivars showed considerable genetic diversity in terms of biomass accumulation, concentration and contents of P and Ca in shoots and roots, P-stress factor (PSF) and P use efficiency. Cultivars showed variable P-stress tolerance, and cultivars depicting low PSF and high P-efficiency values were better adaptable to P-starvation. In experiment 2, after initial feeding on optimum nutrition for 12 d after transplanting (DAT), class-I (low P-tolerant (Oscar and Con-II)) and class-II (low P-sensitive (Gold Rush and RL-18)) cultivars were exposed to P-free environment for 25 d. All of the cultivars remobilized P from above ground parts to their roots during growth in P-free environment, the magnitude of which was variable in tested cultivars. P-concentrations ([P]s) at 37 DAT were higher in developing compared with developed leaves. Translocation of absorbed P from metabolically inactive to active sites in P-stressed plants may have helped class-I cultivars to establish a better rooting system, which provided a basis for enhanced P-utilization efficiency (PUE) and tolerance against P-stress. By supplying TCP and RP spatially separated from other nutrients in split root study, class-I cultivars were still able to mobilize RP and TCP more efficiently compared with class-II cultivars. To compare the growth behavior under P-stress, cultivars were grown in pots for 41 d after sowing, using a soil low in P (NaHCO(3)-extractable P = 3.97 mg/kg, Mehlich-III-extractable P = 6.13 mg/kg) with (+P = 60 mg P/kg soil) or without P addition (0P) in study 4. Tested cultivars showed genetic diversity in PUE, P-efficiency (PE), P-efficiency ratio (PER) and PSF. P-stress markedly reduced biomass and plant P contents. Cultivars that produced higher root biomass accumulated higher total P-contents (r= 0.98**), which in turn was related negatively to PSF (r=-0.95**) and positively to shoot and total biomass. PER and PE showed significant correlations with shoot P-contents and biomass. Cultivars depicting high PUE and PE, and low PSF values showed better growth behavior under low soil P-environment. Systematic analysis and deployment of the plant rescue traits underlying the nutrient acquisition, assimilation, utilization and remobilization under P-starvation will bring more sparingly soluble P into cropping systems and will help to scavenge more P from plant unavailable bound P reserves.

Eco-toxic effects of sulfadiazine sodium, sulfamonomethoxine sodium and enrofloxacin on wheat, Chinese cabbage and tomato

Investigation of the toxic effects of three veterinary drugs [sulfadiazine sodium (SDS), sulfamonomethoxine sodium (SMMS), and enrofloxacin (EFLX)] on seed germination, root elongation and shoot elongation of wheat (Triticum aestivum L.), Chinese cabbage (Brassica campestris L.) and tomato (Cyphomandra betacea) was carried out. Significant linear relationships between the root and shoot elongation and the concentration of veterinary drugs addition were observed. The effects of the three veterinary drugs on seed germination of wheat, Chinese cabbages and tomato were not significant (P > 0.05), but on shoot and root elongation they were markedly significant (P < 0.05). The inhibitory rates of veterinary drugs on root and shoot elongation of crops were significantly stronger than that on seed germination. Based on IC(50) (drugs concentration when 50% plants show inhibition) of root elongation, wheat was the most sensitive plant to the toxicity of SDS with a IC(50) value as high as 28.1 mg/kg; Chinese cabbage was the most sensitive plant to the toxicity of SMMS with a IC(50) value as high as 27.1 mg/kg; tomato was the most sensitive plant to the toxicity of EFLX with a IC(50) value as high as 125.7 mg/kg. The toxic effects of sulfadiazine sodium and sulfamonometh-oxine sodium on the three crops were much higher than that of enrofloxacin.

Growth and elemental accumulation of plants grown in acidic soil amended with coal fly ash-sewage sludge co-compost

A greenhouse experiment was conducted to evaluate the growth and heavy-metal accumulation of Brassica chinensis and Agropyron elongatum in 10 and 25% ash-sludge co-compost (ASC)--amended loamy acidic soil (pH 4.51) at two different application rates: 20% and 40% (v/v). Soil pH increased, whereas electrical conductivity decreased with the amendment of ASC to soil. Bioavailable Cu, Zn, and Mn contents of ASC-amended soil decreased, whereas Ni, Pb, and B contents increased. Concentrations of bioavailable Cu, Zn, and Mn in sludge compost (SC)-amended soils were 5.57, 20.8, and 8.19 mg kg(-1), respectively. These concentrations were significantly lower than those in soil receiving an application rate of 20 or 25% ASC as 2.64, 8.48, and 5.26 mg kg(-1), respectively. Heavy metals and B contents of the composting mass significantly increased with an increase in ASC application rate from 20 to 40% (6.2 to 16.6 mg kg(-1) for 10% ASC- and 9.4 to 18.6 mg kg(-1) for 25% ASC-amended soil. However, when the ash content in co-compost increased from 10 to 25% during composting, bioavailable heavy-metal contents decreased. However, B contents increased with an increase in ash content. Addition of co-composts increased the dry-weight yield of the plants, and this increase was more obvious as the ash amendment rate in the co-composts and the ASC application rate increased. In case of B. chinensis, the biomass of 2.84 g/plant for 40% application of 25% ASC was significantly higher than SC (0.352 g/plant), which was 40% application of 10% ASC (0.434 g/plant) treatments. However, in A. elongatum, the differences between biomass of plants grown with 10% (1.34-1.94 g/ plant) and 25% ASC (2.12-2.21 g/plant) were not significantly different. Furthermore, there were fewer plant-available heavy metals in 25% ASC, which decreased the uptake of heavy metals by plants. ASC was favorable in increasing the growth of B. chinensis and A. elongatum. The optimal ash amendment to the sludge composting and ASC application rates were at 25 and 20%, respectively.

Impact of combined exposure of chemical, fertilizer, bio-fertilizer and compost on growth, physiology and productivity of Brassica campestries in old alluvial soil

Field experiment was carried out during November 2006 to February 2007 under old alluvial soil to evaluate the impact of combined dose of chemical fertilizer, biofertilizer in combination with compost for the yellow sarson (Brassica campestries cv. B9) in a randomized block design replicated thrice. Various morpho-physiological parameters viz., plant population, length of shoot and root, leaf area index (LAI), crop growth rate (CGR), net assimilation rate (NAR), yield attributes viz., number of siliquae per plant, number of seeds/siliquae, 1000 seed weight (test weight), seed yield, stover yield and physiological and biochemical parameters viz., pigment content, sugar, amino acid, protein, ascorbic acid content in physiologically active leaf were performed. The treatment T1 i.e., 40% less N fertilizer 25% less P fertilizer K fertilizer constant + 12 kg ha(-1) biofertilizer (Azophos) and organic manure (compost) @ 5Mt ha(-1), showed the maximum chlorophyll accumulation (10. 231 mg g(-1) freshweight), highest seed/siliquae (25.143), test weight of seeds (4. 861g) and highest seed yield (10.661 tha(-1)). A comparison between all the morphological, anatomical, physiological and biochemical parameters due to application of chemical fertilizer; bio-fertilizer and compost alone and in combination and their impact on soil microorganism, flora and fauna will throw a sound environmental information.

Hydrophobic metabolites from Rhododendron formosanum and their allelopathic activities

Eighteen components were isolated from the methanolic extract of leaves of Rhododendron formosanum Hemsl. (Ericaceae), an endemic species in Taiwan, and evaluated for their allelopathic properties. Of the isolated compounds, 3beta-friedelinol, 5,6beta-epoxy-5beta-stigmastan-3beta-ol, 5,6alpha-epoxy-5alpha-stigmastan-3beta-ol, lupeol and ursolic acid revealed inhibitory effects at 10(-4) M or above, whereas alpha-tocopherol, friedelin and beta-amyrin acetate exhibited stimulatory effects on the radicle growth of the test plants at the same concentration or above. However, squalene and alpha-amyrin showed either a stimulatory or inhibitory effect. The remaining four components, coumarin, beta-sitosterol, adian-5-en-3beta-ol and 3beta-acetoxyurs-12-en-28-al, were not significantly effective in the present bioassay, but have been reported as allelopathic agents elsewhere.